Vitamin D receptor gene Fok1 polymorphism predicts calcium absorption and bone mineral density in children

The vitamin D receptor (VDR) gene has been implicated as one of the major g enetic components of osteoporosis. We evaluated the relationship between ma rkers of mineral status and restriction fragment length polymorphisms of th e VDR gene in 72 healthy children age 7-12 years. Using stable isotope tech niques and dual-energy X-ray absorptiometry, we measured dietary calcium ab sorption, bone calcium deposition rates, and total body bone mineral densit y (BMD), The Fok1 polymorphism at the VDR translation initiation site was s ignificantly associated with BMD (p = 0.02) and calcium absorption (p = 0.0 4), Children who were FF homozygotes had a mean calcium absorption that was 41.5% greater than those who were ff homozygotes and 17% greater absorptio n than Ff heterozygotes. BMD was 8.2% greater in the FF genotype than the f f genotype and 4.8% higher than the Ff genotype, These results suggest a su bstantial relationship between the VDR gene and bone metabolism at one or m ore levels, including dietary absorption of calcium and BMD in growing chil dren.